̽��ֱ�� of Cambridge - Lisa Ronan

Childhood obesity linked to structural differences in key brain regions

cjb250 — Wed, 23 Oct 2019 23:01:31 +0000

However, the scientists who led the study stress that it is not possible to say whether obesity causes these brain changes or whether the children are obese because their brain structures are different.

Around 124 million children worldwide are thought to be obese. In the UK, almost one in five children are overweight or obese when they start primary school and this figure increases to one in three by the time they begin secondary school. Children who are overweight or obese are more likely to become obese adults, and have an increased risk of poorer health outcomes in later life including diabetes, heart disease and cancer.

Previous studies have linked being overweight with scoring lower on various measures of executive function, an umbrella term for several functions such as self-control, decision making, working memory (temporarily holding information for processing) and response to rewards. Broadly speaking, executive function refers to a set of processes that enable planning, problem solving, flexible reasoning and regulation of behaviours and emotions.

To examine if this link existed in children, researchers at the ̽��ֱ�� of Cambridge and Yale ̽��ֱ�� analysed data from 2,700 children between the ages of 9-11 years who had been recruited as part of the National Institutes of Health Adolescent Brain Cognitive Development (NIH ABCD) Study. ̽��ֱ��results of their study are published today in the journal Cerebral Cortex.

In particular, the researchers looked at the thickness of the cortex, the outer layer of the brain – our so-called ‘grey matter’ – and compared it to each child’s body mass index (BMI). They also analysed results from tests of executive function.

̽��ֱ��team found an association between increased BMI and significant reductions in the average (mean) thickness of the cortex, as well as thinning in the pre-frontal region of the cortex, an area associated with cognitive control. This relationship remained after accounting for factors including age, sex, race, parental education, household income and birth-weight.

Image: ̽��ֱ��brain areas highlighted in blue represent regions where cortical thickness is related to BMI. ̽��ֱ��lighter the blue, the more pronounced the relationship – in other words, the thinner the cortex is in children with a higher BMI. (Credit: Lisa Ronan, ̽��ֱ�� of Cambridge)

̽��ֱ��researchers also found that increased BMI was associated with poorer performance at tests to measure executive function.

“We saw very clear differences in brain structure between children who were obese and children who were a healthy weight,” says the study’s first author Dr Lisa Ronan from the Department of Psychiatry at the ̽��ֱ�� of Cambridge.

“It’s important to stress that the data does not show changes over time, so we cannot say whether being obese has changed the structure of these children’s brain or whether innate differences in their brains lead them to become obese.”

̽��ֱ��NIH ABCD Study will follow these children as they grow older and Dr Ronan hopes this will enable them to see whether structural differences in the brain change over time and exactly how they relate to obesity. In particular, it may help them understand whether managing a child’s weight will make a difference to their executive function.

When the team used waist circumference and waist-to-height ratio as a measure of obesity, they found that these, too, were associated with reduced executive function, but the link between cortical thickness was more complicated, with some regions showed reduced thickness while others showed increased thickness.

“This unique and openly available dataset has allowed us to examine the relationships between brain structure, cognitive functions and body weight,” adds Professor Paul Fletcher, also at Cambridge’s Department of Psychiatry. “ ̽��ֱ��links that we observed suggest that there are very real structural brain and cognitive differences in children who are obese. ̽��ֱ��findings contribute a small part towards our growing understanding of the causes and consequences of obesity in children.”

̽��ֱ��research was supported by the Bernard Wolfe Health Neuroscience Fund and Wellcome.

Reference
Ronan, L., Alexander-Bloch, A. & Fletcher, P. Childhood obesity, cortical structure and executive function in healthy children. Cerebral Cortex; 24 Oct 2019; DOI: 10.1093/cercor/bhz257

Obesity in children is associated with differences in brain structure in regions linked to cognitive control compared to the brains of children who are normal weight, according to new research from the ̽��ֱ�� of Cambridge.

̽��ֱ��links that we observed suggest that there are very real structural brain and cognitive differences in children who are obese

Paul Fletcher

Shirley810

Pick & Mix sweets

Researcher Profile: Dr Lisa Ronan

Dr Lisa Ronan, a Senior Research Associate and Bernard Wolfe Research Fellow at the Department of Psychiatry, wants to understand the relationship between obesity and the brain.

“ ̽��ֱ��big question is whether obesity causes changes in brain structure or whether it’s differences in brain structure that lead to obesity,” she says. “At the moment, we don’t know the answer, but it potentially has important implications for brain health.”

In adults, being overweight or obese has been linked to an increased future risk of developing Alzheimer’s disease or dementia, while in children, increases in body mass index (BMI) are linked to changes in executive function. By understanding the causal relationship between obesity and brain health, Lisa hopes to help identify the mechanism which underpins this association.

Although Lisa began her career with a degree in Experimental Physics, she moved into a Masters degree in Medical Physics and from there too an interest in neuroimaging, which she says she immediately loved.

“I worked as a research assistant in a hospital, analysing patient MRI images and eventually completed my PhD, which focused on identifying brain differences in certain types of epilepsy.”

Day-to-day, her work is spent writing and running code to analyze data. “ ̽��ֱ��big moments when you press a button and a result pops up are rare. Mostly its just figuring things out, but this is actually the fun bit.”

Lisa says that when she started working in neuroimaging, datasets featured “tens of subjects using fairly intuitive methods”. These days, datasets include tens of thousands of subjects, and ever more complex and sensitive parameters.

“Research works best when done in collaboration, and I am very privileged to have always had terrific colleagues to discuss ideas with, and ask questions of,” she says. “In our department, we are particularly fortunate to attract individuals from many different backgrounds and with different specialties, including medicine, computer science, genetics and physics. This diversity not only enables you to answer a question more quickly than you might otherwise have been able to, but it deepens our understanding and scope of our research.”

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Brains of overweight people ‘ten years older’ than lean counterparts at middle-age

cjb250 — Thu, 04 Aug 2016 09:10:08 +0000

Our brains naturally shrink with age, but scientists are increasingly recognising that obesity – already linked to conditions such as diabetes, cancer and heart disease – may also affect the onset and progression of brain ageing; however, direct studies to support this link are lacking.

In a cross-sectional study – in other words, a study that looks at data from individuals at one point in time – researchers looked at the impact of obesity on brain structure across the adult lifespan to investigate whether obesity was associated with brain changes characteristic of ageing. ̽��ֱ��team studied data from 473 individuals between the ages of 20 and 87, recruited by the Cambridge Centre for Aging and Neuroscience. ̽��ֱ��results are published in the journal Neurobiology of Aging.

̽��ֱ��researchers divided the data into two categories based on weight: lean and overweight. They found striking differences in the volume of white matter in the brains of overweight individuals compared with those of their leaner counterparts. Overweight individuals had a widespread reduction in white matter compared to lean people.

Comparison of grey matter (brown) and white matter (yellow) in sex-matched subjects A (56 years, BMI 19.5) and B (50 years, BMI 43.4). Credit: Lisa Ronan

̽��ֱ��team then calculated how white matter volume related to age across the two groups. They discovered that an overweight person at, say, 50 years old had a comparable white matter volume to a lean person aged 60 years, implying a difference in brain age of 10 years.

Strikingly, however, the researchers only observed these differences from middle-age onwards, suggesting that our brains may be particularly vulnerable during this period of ageing.

“As our brains age, they naturally shrink in size, but it isn’t clear why people who are overweight have a greater reduction in the amount of white matter,” says first author Dr Lisa Ronan from the Department of Psychiatry at the ̽��ֱ�� of Cambridge, “We can only speculate on whether obesity might in some way cause these changes or whether obesity is a consequence of brain changes.”

Senior author Professor Paul Fletcher, from the Department of Psychiatry, adds: “We’re living in an ageing population, with increasing levels of obesity, so it’s essential that we establish how these two factors might interact, since the consequences for health are potentially serious.

“ ̽��ֱ��fact that we only saw these differences from middle-age onwards raises the possibility that we may be particularly vulnerable at this age. It will also be important to find out whether these changes could be reversible with weight loss, which may well be the case.”

Despite the clear differences in the volume of white matter between lean and overweight individuals, the researchers found no connection between being overweight or obese and an individual’s cognitive abilities, as measured using a standard test similar to an IQ test.

Co-author Professor Sadaf Farooqi, from the Wellcome Trust–Medical Research Council Institute of Metabolic Science at Cambridge, says: “We don’t yet know the implications of these changes in brain structure. Clearly, this must be a starting point for us to explore in more depth the effects of weight, diet and exercise on the brain and memory.”

̽��ֱ��research was supported by the Bernard Wolfe Health Neuroscience Fund, the Wellcome Trust and the Biotechnology and Biological Sciences Research Council.

Reference
Ronan, L et al. Obesity associated with increased brain-age from mid-life. Neurobiology of Aging; e-pub 27 July 2016; DOI: 10.1016/j.neurobiolaging.2016.07.010

From middle-age, the brains of obese individuals display differences in white matter similar to those in lean individuals ten years their senior, according to new research led by the ̽��ֱ�� of Cambridge. White matter is the tissue that connects areas of the brain and allows for information to be communicated between regions.

We’re living in an ageing population, with increasing levels of obesity, so it’s essential that we establish how these two factors might interact, since the consequences for health are potentially serious

Paul Fletcher

Ben Watkin

Measuring tape

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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